The present invention relates to a foldable device such as portable cellular phone, word processor and personal computer, and in particular to an apparatus for detecting the opening and closing angle thereof.
The foldable portable cellular phones have heretofore been provided with means for detecting the opening of its housing in order to prevent the wasteful Power consumption when folded or to prevent, so-called howling (picking up of sounds) due to the proximity between a microphone and a receiver from occurring. For further information on the prior art for detecting the magnetic force lines from a magnet, refer to Japanese Patent Kokai Publication JP-A-10-126469, JP-A-11-27352. For further information on the prior art using a push-switch, refer to JP-A-9-93316.
An exemplary prior art will be described with reference to the drawings. FIGS. 3A and 3B show an exemplary prior art foldable portable cellular phone when it is opened and closed, respectively. The foldable portable cellular phone 101 has means for detecting the opening and closing of the phone, comprising a magnet 104 which is mounted on a first housing 102 on the display side of the phone and a reed switch 105 which is mounted on a second housing 103 on the operation side of the phone. The folded condition of the phone is sensed by detecting the magnetic forces from the magnet 104 on the display side by means of the reed switch 105 on the operation side. This detection turns off the power source for the speech circuitry of the microphone 106 and the receiver 107 (to bring the Phone into a non-speech call mode) for preventing the howling from occurring.
Since the closing or opening is detected immediately before the phone is closed in the prior art, there is a problem that howling due to the proximity between the microphone and the receiver can not be Prevented before the phone is brought into the non-speech call mode. In particular, the means for detecting the magnetic force lines has a disadvantage that the margin of howling, that is the angle at which the phone is brought into non-speech mode can not be increased since such means detects the condition immediately before the phone is folded. There is also a problem the magnetic force fluxes emitted from the magnet may give an adverse influence upon the other circuit components or wrong detection may be conducted due to the magnet in the receiver, etc. Use of detecting means such as push-switch or magnet and reed switch is not advantageous for reduction in size and weight of the Portable cellular phone since a given space is occupied in the housing and predetermined Parts are required.
In association with the advent of recent multifunction portable cellular phones, hands-free speech call via a laud speaker of the phone which is laid on a desk or the like and character communication using the cellular Phone has been generally conducted in addition to normal speech call by closing the receiver and microphone units to the ear and mouth, respectively. In Particular, hands-free speech call is advantageous in that safe speech call is possible while driving an automobile. When the foldable phone is laid so that it is folded at a given angle, it is advantageously possible to view the display and/or listen the voice. If the mode of the phone can be automatically changed depending upon the folding angle, for example, it is in normal speech call and hands-free speech call mode when the phone is flat and is folded in a given angle, respectively, it is convenient. Further, it is more convenient if the modes can be changed depending upon the folding angle in association with the addition of new functions in future.
It is a main aspect of the invention to provide an apparatus for detecting the opening and closing angle, which is easy to conduct switching, reliable and is capable of positively preventing howling from occurring.
It is another aspect of the present invention to provide an apparatus for detecting the opening and closing angle, using no special parts and having reduced size and weight.
In a first aspect of the present invention, an apparatus for detecting the opening and closing angle is characterized in that the apparatus comprises a first and second hinge portions belonging to a first and second housings, respectively for pivotally linking the first housing to the second housing,
in that the first hinge portion has a convex curved surface in a rotational direction of the first housing and comprises a given number of parallel electrodes extending in a rotational direction of the first housing on the curved surface, in that the curved surface portion is disposed in the second housing; in that the second housing includes therein a given number of terminals which are in pressure contact with the electrodes or the curved surface; and in that the terminals are in contact or non-contact with corresponding electrodes at different predetermined angles depending on the rotation of the first housing.
In the apparatus for detecting the opening and closing angle of the Present invention, it is preferable that the electrodes have different lengths extending in parallel with each other and in that the terminals are aligned at their tip ends, have a given length and are in parallel with each other.
In the apparatus for detecting the opening and closing angle of the present invention, it is preferable that the electrodes are aligned with each other at their ends, have a given length and are in parallel with each other, and in that the terminals are at their ends in pressure contact with corresponding electrodes in different their positions in a rotational direction thereof.
In the apparatus for detecting the opening and closing angle of the present invention, it is preferable that the curved surface of the first hinge portion has grooves for guiding the terminals along the corresponding electrodes and their extensions.
In the apparatus for detecting the opening and closing angle of the present invention, it is preferable that the terminals are springs.
In a second aspect of the present invention, the foldable device is characterized in that the device has the apparatus for detecting the opening and closing angle in the first aspect of the present invention.
In the present invention, it is preferable that the foldable device is a Portable cellular phone, a word processor or a personal computer.
In the present invention, it is preferable that the terminals are at least three in number, and the foldable device is a portable cellular phone having a plurality of speech call modes so that it can be changed into any one of normal speech call mode, hands-free speech call mode and non-speech call mode.